Pemphigoid gestationis is also known as herpes gestationis, although the latter name is misleading since this condition is not associated with any virus. This is a rare, itchy, autoimmune disease that occurs during the second and third trimesters of pregnancy and around the time of delivery. Pemphigoid gestationis occurs in 1 per 7,000 to 50,000 pregnancies.
Appearance
Pemphigoid gestationis begins with very itchy, red hives or small bumps around the belly button. Within days to weeks, the rash spreads, and the hives and bumps join to form bizarrely shaped circular patches that cover a wide area of skin. The rash can involve the trunk, back, buttocks, forearms, palms, and soles. It usually does not involve the face, scalp, and inside of the mouth. After 2 to 4 weeks of this rash, large, tense blisters form at the edges of the rash or in apparently normal skin. These blisters heal without scarring if they do not get infected.
This condition usually starts during the second or third trimester, although it has been reported in the first trimester and a short time after delivery. The average appearance is at 21 weeks gestation. Spontaneous clearing of the rash may occur later in the pregnancy, but uncomfortable flares occur immediately prior to delivery in 75% to 80% of women. The rash may also recur when menses resumes or with the use of oral contraceptives. With subsequent pregnancies, pemphigoid gestationis usually recurs earlier and may be more severe. Only 8% of women do not develop pemphigoid gestationis in subsequent pregnancies.
Diagnosis
The cause of pemphigoid gestationis is autoimmune. Antibodies attach to certain types of connective tissue in the skin and cause an inflammatory response. This response is manifested by redness, itching, swelling, and blister formation. Pemphigoid gestationis is diagnosed by taking skin biopsies of different areas of the rash and normal-appearing skin. A special test to detect antibodies called direct immunofluorescence is performed on the biopsies to make the diagnosis.
Treatment
A few women with very mild cases of pemphigoid gestationis can be treated with steroid creams and antihistamines. However, the majority of women require oral steroids to control their symptoms. A high dose is usually used to get symptoms under control and then tapered as the rash improves.
Effect on Baby
Because antibodies cross the placenta, the antibodies that cause pemphigoid gestationis can affect the baby. A noticeable rash has been reported in 5% of newborns born to moms with this condition. This newborn rash is transient and resolves on its own without treatment. There is evidence that women with pemphigoid gestationis have an increased risk of premature delivery. Current studies indicate that there is not an increased risk of miscarriage or stillbirth.
